PaulZC
commented
3 years ago Hi JR (@jerabaul29), Thanks for your interest in the Global Tracker. I've just done a quick test and the sleep current is approximately 250uA. That's probably higher than usual as I haven't used this board for a while and the RTC battery will be charging. I'll leave it for a few hours and will check it again. The second part of your question is more complex. It of course depends what batteries you are using and how often you are transmitting. The bulk of the power goes into charging the super capacitors for the Iridium transmit. I did use an earlier - less efficient - version of the tracker to track a balloon flight:
- Using three AA Energizer Ultimate Lithium
- During the flight the beacon was transmitting every 3 minutes and sent 140 messages
- The payload ended up in a tree and it was weeks before we could pick it up
- Transmitting twice per day for a month, it sent another 50 messages
- We then set it to transmit once per day and it sent another 17 messages before we finally collected it
- Battery voltage at the end was just under 4.0V. It was still quite happy.
- The flight ended up in a tree in Austria in March (2019). Daytime temperatures were around 0C. Heavy snow was the main thing from preventing us from collecting it.
The core design is very robust. We've had a lot of fun with it over the years. There's a paper here that you might enjoy: http://arxiv.org/abs/1904.04321 Best wishes, Paul
jerabaul29
Hi,
I see that you have a "low power" sketch and several mentions of "low power" uses, including recommending some batteries in the hardware overview.
Do you have some actual measurements of how much energy is typically used for transmitting / receiving a message, and the typical current draw of the uC in deep sleep as for example in the https://github.com/sparkfunX/Artemis_Global_Tracker/tree/master/Software/examples/Example12_TestLowPower sketch?
And / or said otherwise: if using 3 AA lithium batteries, and transmitting the GPS position once every 3 hours and doing nothing else (ie deep sleep for 3 hours, getting a GPS reading, sending it through Iridium), how long can I typically expect the module to work before the battery is empty?